Title: Crystallization Mechanism and Charge Carrier Transport in MAPLE-Deposited Conjugated Polymer Thin Films

Abstract

Although spin casting and chemical surface reactions are the most common methods used for fabricating functional polymer films onto substrates, they are limited with regard to producing films of certain morphological characteristics on different wetting and nonwetting substrates. The matrix-assisted pulsed laser evaporation (MAPLE) technique offers advantages with regard to producing films of different morphologies on different types of substrates. Here, we provide a quantitative characterization, using X-ray diffraction and optical methods, to elucidate the additive growth mechanism of MAPLE-deposited poly(3-hexylthiophene) (P3HT) films on substrates that have undergone different surface treatments, enabling them to possess different wettabilities. We show that MAPLE-deposited films are composed of crystalline phases, wherein the overall P3HT aggregate size and crystallite coherence length increase with deposition time. A complete pole figure constructed from X-ray diffraction measurements reveals that in these MAPLE-deposited films, there exist two distinct crystallite populations: (i) highly oriented crystals that grow from the flat dielectric substrate and (ii) misoriented crystals that preferentially grow on top of the existing polymer layers. The growth of the highly oriented crystals is highly sensitive to the chemistry of the substrate, whereas the effect of substrate chemistry on misoriented crystal growth is weaker. The use of a self-assembledmore » monolayer to treat the substrate greatly enhances the population and crystallite coherence length at the buried interfaces, particularly during the early stage of deposition. Furthermore, the evolution of the in-plane carrier mobilities during the course of deposition is consistent with the development of highly oriented crystals at the buried interface, suggesting that this interface plays a key role toward determining carrier transport in organic thin-film transistors.« less

Authors:

Dong, Ban Xuan  ^[1];

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Strzalka, Joseph ^[2]; Jiang, Zhang ^[2]; Li, Huanghe ^[3]; Stein, Gila E. ^[4]; Green, Peter F.  ^[5]

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+ Show Author Affiliations

1. Univ. of Michigan, Ann Arbor, MI (United States); The Univ. of Chicago, Chicago, IL (United States)
2. Argonne National Lab. (ANL), Argonne, IL (United States)
3. Univ. of Michigan, Ann Arbor, MI (United States)
4. Univ. of Tennessee, Knoxville, TN (United States)
5. Univ. of Michigan, Ann Arbor, MI (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)

Publication Date:

2017-11-23

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

National Science Foundation (NSF), Directorate for Mathematical and Physical Sciences Division of Materials Research (MPS-DMR); Vietnam Education Foundation; University of Michigan; USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1415483

Grant/Contract Number:  

AC02-06CH11357

Resource Type:

Journal Article: Accepted Manuscript

Journal Name:

ACS Applied Materials and Interfaces

Additional Journal Information:

Journal Volume: 9; Journal Issue: 51; Journal ID: ISSN 1944-8244

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; MAPLE; X-Ray diffraction; conjugated polymers; crystallization; structure-transport relationship